I. Field of the Invention
This invention relates generally to a hand tool for smoothing or finishing the surface of a workpiece, and more particularly to a hand sanding apparatus for supporting a flexible strip of abrasive sheet material thereon and which can be flexed to conform to arcuate surfaces while maintaining the abrasive sheet in a taut condition.
II. Discussion of the Prior Art
In the manufacture and repair of a variety of products, it is necessary to sand or abrade the product to a desired degree of smoothness. For example, in automobile body and fender repair or in the repair of boat hulls and the like, dents, gouges and other imperfections are first filled with an appropriate filling material and then, once hardened, the surface is sanded smooth prior to painting. Likewise, in the refinishing of certain furniture items, following the removal of the old finish, it is common practice to sand the piece to remove any dents, depressions or gouges in the wood prior to its being restained and revarnished.
The hand sanding operation of plane surfaces is often facilitated by using a sanding block. Most prior art sanding blocks are rigid and include a planar surface over which the sandpaper or other abrasive sheet is wrapped. The block may also include a handle for facilitating the gripping thereof during use. While a flat, rigid sanding block may be satisfactory for treating or finishing a planar surfaces, e.g., a tabletop, it is wholly unsuitable for finishing contoured surfaces.
In treating contoured surfaces, it has been the practice in the past for the user to merely grip the abrasive sheet in his or her hand and use the palm of the hand and the fingers as the backup for the sandpaper. In many instances, the end results are unsatisfactory because of irregularities or waves in the workpiece resulting from the application of uneven pressure during the sanding process.
Ideally, for smoothly contoured surfaces of fairly large radius of curvature, a flexible backup member for the abrasive sheet might produce satisfactory results, but this approach presents difficulty when it is considered that the abrasive sheet is inelastic and, therefore, unable to extend and contract as the backup member is flexed to conform to the contours of the surface being abraded. When sanding a convex surface, the backing member must flex to a concave condition, thus leaving the abrasive sheet draped over it in a loose-fitting manner. When sanding a concave surface, on the other hand, the backing member must flex to a convex orientation and the degree to which flexure is permitted is determined by the span between the sandpaper clamps used to secure the sandpaper to the backup member.